Large-base wind and light storage and regulation combined power generation system

Abstract

The utility model relates to a large-base wind and light storage and regulation combined power generation system, which mainly comprises a three-winding boosting transformer with centralized energy storage, a phase modifier, a filter branch and a split winding wiring mode, a starting point of an extra-high voltage direct current project, centralized energy storage and a high-voltage side of a three-winding boosting transformer are connected in parallel to a high-voltage bus of a booster station; the three-winding boosting transformer is grounded through a neutral point small reactor; a small-resistance grounding branch, a wind power collection bus, a distributed energy storage collection line, a phase modifier, a filtering branch and a first split winding of a three-winding boosting transformer are connected in parallel to a wind power low-voltage collection bus; and the small-resistance grounding branch, the photovoltaic collection bus, the distributed energy storage collection circuit, the phase modifier, the filtering branch and a second split winding of the three-winding boosting transformer are connected in parallel to the photovoltaic low-voltage collection bus. According to the utility model, the equipment type selection and configuration scheme of the collection booster station of the new energy large base is improved, the short-circuit current level is reduced, the stability of a power generation curve is improved, and the stability and economical efficiency of cross-regional power transmission of the new energy large base are improved.

Description

Technical Field

[0001] The utility model relates to the application fields of grid-connected power generation, energy storage and phase modulation of large-scale new energy bases, and specifically to a large-scale wind, solar, energy storage and modulation combined power generation system. Background Art

[0002] The planned installed capacity of wind farms and photovoltaic power stations in large new energy bases is huge, generally exceeding one million kilowatts. It is necessary to build on-site booster stations to bundle and collect the currents and then transmit them at a higher voltage level. Problems such as large working current and high short-circuit current level on the low-voltage side of the booster stations are often encountered, which makes it difficult to select electrical equipment and limits the ability of a single station to collect new energy.

[0003] Traditional large-scale wind and solar power plant boosting and grid-connected systems such as Figure 2 As shown, the public grid and the high-voltage side of the double-winding step-up transformer are connected to the high-voltage bus of the step-up station, the wind power collection bus, distributed energy storage, and SVG are connected to the wind power low-voltage collection bus, the photovoltaic collection bus, distributed energy storage, and SVG are connected to the photovoltaic low-voltage collection bus, the wind power low-voltage collection bus is connected to the double-winding transformer bus, and the photovoltaic low-voltage collection bus is connected to the double-winding transformer bus. This wind farm and photovoltaic power station both adopt the structure of an independent step-up grid-connected system, which makes the equipment utilization rate low and the equipment rated current large.

[0004] At the same time, the volatility and uncertainty of renewable energy power generation cannot provide rotational inertia for the power system. These are well-known defects. Therefore, on the one hand, energy storage needs to be configured to achieve peak shaving and valley filling and smooth fluctuations. On the other hand, small phase-shifting phases need to be installed to improve the short-circuit ratio of renewable energy multi-stations and enhance system stability. For large renewable energy bases, there is a risk of large-scale disconnection from the grid when high and low voltage crossing or DC pole locking faults occur. It is usually necessary to configure energy storage and distributed phase-shifting phases based on the principle of layering and zoning to provide reactive voltage support capabilities and better play a stabilizing and regulating role. Utility Model Content

[0005] The utility model provides a large-scale wind-solar-storage-regulation combined power generation system, which is beneficial to improving the equipment selection and configuration scheme of the new energy collection booster station, and enhancing the stability and economy of cross-regional power transmission of large new energy bases.

[0006] The technical solution adopted by the utility model to solve the above technical problems is as follows:

[0007] A large-scale wind, photovoltaic, storage and modulation combined power generation system, including a starting point of a UHV DC project, a high-voltage busbar of a booster station, a three-winding booster transformer, a low-resistance grounding branch, a wind power low-voltage collection busbar, a photovoltaic low-voltage collection busbar, a wind power collection busbar, a photovoltaic collection busbar, and a distributed energy storage collection branch; including centralized energy storage, a phase regulator, and a filter branch, and the three-winding booster transformer is a split winding connection method; the specific structure is: the starting point of the UHV DC project, centralized energy storage, and the high-voltage side of the three-winding booster transformer are connected in parallel to the high-voltage busbar of the booster station; the three-winding booster transformer is grounded through a small neutral reactance; the low-resistance grounding branch, the wind power collection busbar, the distributed energy storage collection line, the phase regulator, the filter branch, and the first split winding of the three-winding booster transformer are connected in parallel to the wind power low-voltage collection busbar; the low-resistance grounding branch, the photovoltaic collection busbar, the distributed energy storage collection line, the phase regulator, the filter branch, and the second split winding of the three-winding booster transformer are connected in parallel to the photovoltaic low-voltage collection busbar.

[0008] A large-scale wind-solar-storage-regulation combined power generation system comprises a starting point of an ultra-high voltage direct current project, a high-voltage busbar of a booster station, a double-winding booster transformer, a low-resistance grounding branch, a wind power low-voltage collection busbar, a photovoltaic low-voltage collection busbar, a wind power collection busbar, a photovoltaic collection busbar, and a distributed energy storage collection branch; it comprises centralized energy storage, a phase regulator, and a filter branch, and the double-winding booster transformer is a double-branch wiring method; the specific structure is as follows: the starting point of the ultra-high voltage direct current project, the centralized energy storage, and the high-voltage side of the double-winding booster transformer are respectively connected in parallel to the high-voltage busbar of the booster station; the double-winding booster transformer is grounded through a small reactance at the neutral point; the low-resistance grounding branch, the wind power collection busbar, the distributed energy storage collection line, the phase regulator, the filter branch, and the first branch busbar of the double-winding booster transformer are respectively connected in parallel to the wind power low-voltage collection busbar; the low-resistance grounding branch, the photovoltaic collection busbar, the distributed energy storage collection line, the phase regulator, the filter branch, and the second branch busbar of the double-winding booster transformer are respectively connected in parallel to the photovoltaic low-voltage collection busbar.

[0009] The innovative features and technical effects of the utility model are described in detail as follows:

[0010] First, it is proposed to use split winding or double branch connection to realize transformer sharing mode. Traditionally, wind farms and photovoltaic power stations use independent boosting grid-connected systems, with low equipment utilization and large equipment rated current. The utility model proposes to replace the traditional two-winding transformer and single busbar combination mode with split winding transformer or double winding transformer double branch connection, which is conducive to achieving the purpose of wind power and photovoltaic sharing the main transformer capacity and the use of large-capacity main transformer in new energy boosting stations, while reducing short-circuit current and equipment rated working current, reducing the number of equipment and site occupation area, and improving equipment utilization and economy; in view of the problem that the short-circuit current of large new energy bases is large and the single-phase short-circuit current is greater than the three-phase short-circuit current, the grounding method of the neutral point of the boosting transformer is improved, and it is proposed that the neutral point of the transformer in the large new energy base is changed from the conventional direct grounding method to the grounding method through a small reactance, which can effectively suppress the single-phase short-circuit current on the low-voltage side and reduce the harm of the short-circuit current back to the power grid, thereby improving the safety and stability of the power grid.

[0011] Secondly, a mode of sharing centralized energy storage and distributed energy storage is proposed. Traditional energy storage is connected to the low-voltage side of wind farms and photovoltaic stations to achieve the initial stabilization of new energy output, but it cannot take into account the auxiliary services of peak and frequency regulation in the region, and the economic benefits are poor. The utility model adds centralized energy storage on the high-voltage bus side of the booster station to take into account the auxiliary services in the region and play the role of stabilizing the output of new energy in the region. It can respond to the output of new energy according to the DC transmission curve to achieve secondary fine regulation, and improve the stability and economy of cross-regional power transmission of large new energy bases.

[0012] Finally, a method to improve the power quality and short-circuit ratio of the power grid is proposed. Filter branches are added to the wind power low-voltage collection bus and photovoltaic low-voltage collection bus to reduce grid harmonics, and the traditional SVG dynamic reactive compensation device is replaced with a distributed phase regulator to improve the short-circuit ratio, system inertia and stability of multiple renewable energy stations, give full play to the reactive power of the system, and provide sub-transient, transient and steady-state voltage support for renewable energy stations, and prevent the occurrence of wind power and photovoltaic grid disconnection caused by high and low voltage crossing or DC pole locking failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0014] Figure 2 This is a schematic diagram of the structure of the boosting and grid-connected system of a traditional large-scale wind and solar power plant;

[0015] In the figure: 1—starting point of UHV DC project, 2—centralized energy storage, 3—high voltage busbar of booster station, 4—three-winding booster transformer, 5—double-winding booster transformer, 6—small reactor at center point, 7—wind power low-voltage collection busbar, 8—photovoltaic low-voltage collection busbar, 9—small resistance grounding branch, 10—wind power collection busbar, 11—photovoltaic collection busbar, 12—distributed energy storage collection line, 13—phase regulator, 14—filter branch, 15—double branch connection, 16—grounding resistor, 17—SVG, 18—public grid. DETAILED DESCRIPTION

[0016] Embodiment 1, as Figure 1 A large-scale wind, photovoltaic, storage and modulation combined power generation system, including a UHV DC project starting point 1, a booster station high-voltage bus 3, a three-winding boost transformer 4, a small resistance grounding branch 9, a wind power low-voltage collection bus 7, a photovoltaic low-voltage collection bus 8, a wind power collection bus 10, a photovoltaic collection bus 11, and a distributed energy storage collection branch 12; including a centralized energy storage 2, a phase regulator 13, and a filter branch 14, and the three-winding boost transformer 4 is a split winding connection mode; the specific structure is: the UHV DC project starting point 1, the centralized energy storage 2, ... The high-voltage side of the transformer 4 is connected in parallel to the high-voltage bus 3 of the substation; the three-winding step-up transformer 4 is grounded through a small neutral point reactor 6; the low-resistance grounding branch 9, the wind power collection bus 10, the distributed energy storage collection line 12, the phase regulator 13, the filter branch 14, and the first split winding of the three-winding step-up transformer 4 are connected in parallel to the wind power low-voltage collection bus 7; the low-resistance grounding branch 9, the photovoltaic collection bus 11, the distributed energy storage collection line 12, the phase regulator 13, the filter branch 14, and the second split winding of the three-winding step-up transformer 4 are connected in parallel to the photovoltaic low-voltage collection bus 8.

[0017] Embodiment 2, as Figure 1A large-scale wind, photovoltaic, storage and modulation combined power generation system, including a UHV DC project starting point 1, a booster station high-voltage bus 3, a double-winding boost transformer 5, a low-resistance grounding branch 9, a wind power low-voltage collection bus 7, a photovoltaic low-voltage collection bus 8, a wind power collection bus 10, a photovoltaic collection bus 11, and a distributed energy storage collection branch 12; including a centralized energy storage 2, a phase regulator 13, and a filter branch 14, and the double-winding boost transformer 5 is a double-branch wiring method; the specific structure is: the UHV DC project starting point 1, the centralized energy storage 2, the double-winding boost transformer 5 high-voltage sides are respectively connected in parallel to the high-voltage bus 3 of the substation; the double-winding step-up transformer 5 is grounded through a small neutral point reactor 6; the low-resistance grounding branch 9, the wind power collection bus 10, the distributed energy storage collection line 12, the phase regulator 13, the filter branch 14, and the first branch bus of the double-winding step-up transformer 5 are respectively connected in parallel to the wind power low-voltage collection bus 7; the low-resistance grounding branch 9, the photovoltaic collection bus 11, the distributed energy storage collection line 12, the phase regulator 13, the filter branch 14, and the second branch bus of the double-winding step-up transformer 5 are respectively connected in parallel to the photovoltaic low-voltage collection bus 8.

[0018] The utility model adopts a three-winding step-up transformer or a double-winding step-up transformer with double-branch connection to replace the traditional double-winding transformer and single busbar connection combination. The winding capacity on the high-voltage side can be shared by wind power and photovoltaic power, and the split winding on the low-voltage side is used for access to wind power and photovoltaic power respectively, that is, the two low-voltage split windings of the three-winding step-up transformer collect photovoltaic power and wind power respectively, and share the high-voltage side winding of the three-winding transformer; the low-voltage side of the double-winding step-up transformer is used for access to wind power and photovoltaic power respectively through the first and second branch buses of the double-branch connection, and share the high-voltage side winding. The direct grounding of the neutral point of the step-up transformer is replaced by a small reactance grounding method, the distributed phase regulator is replaced by the traditional SVG reactive compensation device, and the filtering branch is added, which improves the short-circuit ratio, moment of inertia and system stability, and reduces the probability of large new energy bases being disconnected from the grid due to grid harmonics, high and low voltage crossing or DC pole locking failure. The comprehensive application of centralized and distributed energy storage takes into account the regional auxiliary services and the stabilizing effect of new energy output, responds to ultra-high voltage direct current to achieve refined regulation of large-scale new energy base systems, and improves the economy of large-scale new energy base systems and the safety and stability of the power system.

Claims

1. A large-scale wind, solar, storage and dispatching combined power generation system, including a UHV DC project starting point, a high-voltage busbar of a booster station, a three-winding booster transformer, a low-resistance grounding branch, a wind power low-voltage collection busbar, a photovoltaic low-voltage collection busbar, a wind power collection busbar, a photovoltaic collection busbar, and a distributed energy storage collection branch; characterized in that: The invention comprises a centralized energy storage (2), a phase regulator (13), and a filter branch (14), wherein the three-winding step-up transformer (4) is connected in a split winding connection mode; the specific structure is as follows: the starting point (1) of the ultra-high voltage direct current project, the centralized energy storage (2), and the high voltage side of the three-winding step-up transformer (4) are connected in parallel to the high voltage bus (3) of the step-up station; the three-winding step-up transformer (4) is grounded through a small neutral point reactance (6); the small resistance grounding branch (9), the wind power collection bus (10), the distributed energy storage collection line (12), the phase regulator (13), the filter branch (14), and the first split winding of the three-winding step-up transformer (4) are connected in parallel to the wind power low voltage collection bus (7); the small resistance grounding branch (9), the photovoltaic collection bus (11), the distributed energy storage collection line (12), the phase regulator (13), the filter branch (14), and the second split winding of the three-winding step-up transformer (4) are connected in parallel to the photovoltaic low voltage collection bus (8).

2. A large-scale wind, solar, storage and dispatching combined power generation system, including a UHV DC project starting point, a high-voltage busbar of a booster station, a double-winding booster transformer, a low-resistance grounding branch, a wind power low-voltage collection busbar, a photovoltaic low-voltage collection busbar, a wind power collection busbar, a photovoltaic collection busbar, and a distributed energy storage collection branch; characterized in that: The invention comprises a centralized energy storage (2), a phase regulator (13), and a filter branch (14), wherein the double-winding step-up transformer (5) is connected in a double-branch wiring mode; the specific structure is as follows: the starting point (1) of the ultra-high voltage direct current project, the centralized energy storage (2), and the high-voltage side of the double-winding step-up transformer (5) are respectively connected in parallel to the high-voltage busbar (3) of the step-up station; the double-winding step-up transformer (5) is grounded via a small neutral point reactor (6); the low-resistance grounding branch (9), the wind power collection busbar (10), the distributed energy storage collection line (12), the phase regulator (13), the filter branch (14), and the first branch busbar of the double-winding step-up transformer (5) are respectively connected in parallel to the wind power low-voltage collection busbar (7); the low-resistance grounding branch (9), the photovoltaic collection busbar (11), the distributed energy storage collection line (12), the phase regulator (13), the filter branch (14), and the second branch busbar of the double-winding step-up transformer (5) are respectively connected in parallel to the photovoltaic low-voltage collection busbar (8).

Images